Bluetooth: Only keep controller up after init if powered on

When a new controller gets added to the system, it needs to be brought
up briefly to read basic information like features, BD_ADDR etc. and
after a timeout it will be brought back down.

The only command that should overwrite this timeout is the set power
command from the management interface. Just reading the controller
list or information is not a good reason to keep the controller up.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>